Importance Effective interventions are needed to support the cocreation of diabetes care plans that are sensible, desirable, and feasible for the people living with diabetes (ie, care that fits). Objective To investigate whether an agenda-setting kit (ASK) added to usual primary care improves fit of care and glycemic control in adults with type 2 diabetes (T2D). Design, Setting, and Participants This single-center, clinician-level cluster randomized clinical trial was conducted from February 16, 2023, to July 26, 2024, with a 6-month follow-up, at a federally qualified health center in New Haven, Connecticut. Eligible clinicians were primary care physicians, nurse practitioners, and physician assistants who prescribed medication to treat patients with T2D. Eligible patients were English- or Spanish-speaking adults aged 18 years or older with T2D and hemoglobin (Hb) A 1c level greater than 8%. Patients were excluded if their clinician determined that an HbA 1c level 8% or lower was inconsistent with goals of care. Data were analyzed from November 7, 2024, to August 13, 2026. Intervention Clinicians were randomized 1:1 to the ASK plus usual primary care group (intervention group) or usual primary care only (control group). The ASK intervention consisted of 14 conversation cards about life with diabetes and its treatment. Prior to the clinical encounter, patients were asked to select 0 to 3 cards they wanted to prioritize for discussion. Main Outcomes and Measures The primary outcome was the 6-month change from baseline in illness intrusiveness measured with the Illness Intrusiveness Ratings Scale (IIRS; range: 13-91, with higher scores indicating greater intrusiveness) and HbA 1c level. Secondary outcomes included changes in treatment burden measured with the Treatment Burden Questionnaire (TBQ; range: 0-150, with higher scores indicating greater burden), diabetes distress measured with the 17-Item Diabetes Distress Scale (DDS-17; scores: indicate little or no distress [<2.0], moderate distress [2.0-2.9], and high distress [≥3.0]), and visit satisfaction. Results Eleven clinicians (6 [54.5%] female) were included in the trial along with 143 of their patients. The mean (SD) patient age was 56 (12) years; 87 participants (60.8%) were female and 88 (61.5%) reported Spanish as their primary language. Six-month survey data were available for 65 of 74 patients (87.8%) in the intervention group and 58 of 69 (84.0%) in the control group; data on HbA 1c level were available for 71 (95.9%) and 65 (94.2%), respectively. At 6 months, mean (SD) IIRS scores were 32.1 (15.1) and 37.1 (18.7) in the intervention and control groups (adjusted mean difference, −3.9; 95% CI, −10.4 to 2.6). The mean (SD) HbA 1c levels were 8.8% (1.8) in the intervention group and 9.1% (1.8) in the control group (adjusted mean difference, −0.2%; 95% CI, −0.9% to 0.5%). Mean (SD) TBQ scores in the intervention and control groups were 41.2 (44.8) and 46.8 (44.4) (adjusted mean difference, 1.0; 95% CI, −16.6 to 18.6), and mean (SD) DDS-17 scores were 2.0 (1.0) and 2.3 (1.0) (adjusted mean difference, −0.1; 95% CI, −0.4 to 0.2). Clinician-reported satisfaction was greater in the intervention group; patient satisfaction did not differ between groups. Conclusions and Relevance In this cluster randomized clinical trial of adults with T2D, use of the ASK with usual primary care was associated with greater clinician satisfaction but not with improvements in patients’ fit of care or glycemic control over 6 months. Larger studies should evaluate interventions that not only identify patients’ priorities and treatment burdens but also better support clinicians in addressing them. Trial Registration ClinicalTrials.gov Identifier: NCT05553912